This application proposes the continuation of a computerized data analysis center to answer unsolved problems in the current management of valvular heart disease. As an established national resource for research into and clinical management of valvular heart disease, the University of Oregon Health Sciences Center has an extensive existing data base to which new information is continually being added. Problems to be considered include: an assessment of long-term postoperative functional results in relation to preoperative risk factors and prognostic variables - with particular attention to optimum timing of valve replacement prior to irreversible deterioration of ventricular function; and an appraisal of results with advanced design cloth-covered prostheses with particular regard to the possibility that anticoagulants are no longer needed. A coordinated computer center for data collection, storage, retrieval and analysis permits integrated management of a data base too large for conventional techniques of data handling, so that the questions posed in this proposal may be answered. Without the use of such techniques, the clinical heterogeneity of patients undergoing surgery creates a myriad of "risk factor" subgroups that are not readily differentiated. With computer identification of homogeneous subsets of patients, the results of clinical trials and studies become more meaningful and clinically applicable.